Heat exchangers



Jan. 16, 1968 w, ERNEST 3,363,679

HEAT EXCHANGERS Original Filed Nov. 9, 1964 15% zmmfw A FOP/V5 VS UnitedStates Patent 3,363,679 HEAT EXCHANQERES Walter Ernest, London, England,assignor, by rncsne assignments, to The American Schach Company, Inc,Pittsburgh, Pa, a corporation of Delaware Continuation of applicationScr. No. 409,533, Nov. 9, 1964. This application Aug. 15, 1966, Ser. No.572,628 Claims priority, application Great Britain, Nov. '7, 1963,44,054/ 63 10 Claims. (Cl. 165-141) This is a continuation ofapplication Ser. No. 409,883, filed Nov. 9, 1964, now abandoned.

The invention relates to heat exchangers and particularly to dual flowheat exchangers.

Known heat exchangers have the disadvantage that the outlet temperatureof the fluid of the secondary cycle can only be regulated by varying therates of flow or inlet temperatures of one or both of the cycles.

The invention has among its objects to provide a heat exchanger in whichthe rate of exchange of heat is readily Changeable.

According to the invention there is provided an cxchanger for heattransference between fluids at different temperatures comprising acircuit for a primary fluid and at least two secondary circuits ofdifferent lengths having a common outlet for a secondary fluid.

According to the invention furthermore means are provided for varyingthe ratio of rates of flow of secondary fluid in the secondary circuitsto control the temperature of the fluid at the common outlet.

Thus the exchanger may be provided as an upright elongated body formedof three concentric tubes, the inlets to the two secondary circuitsbeing provided at the upper end of the two innermost tubes and theprimary fluid flowing in the annular space between the outermost tubeand the next innermost tube. This space is also provided with twohelical coils through which passes the secondary fluid. The innermosttube is in communication With the lower coil at the lower end and thenext outermost tube is in communication with the upper coil at aposition intermediate the ends of the exchanger. At this position thetwo coils are in communication with one another. Thus two secondarycircuits are formed one comprising theinnerrnost tube and the lower andupper coils, and the other comprising the next innermost tube and theupper coil. The circuits have a common outlet.

According to the invention further, the innermost tube, the nextinnermost tube and the upper and lower coils are provided to be readilyremovable from the exchanger whereby the coils may be replaced by othercoils having a different ratio of effective lengths one to another.

Thus the two inner tubes and the coils may be supported by a flanged capWhich is supported by the outermost tube, which tube is advantageouslylined with a refractory material, in such manner that they may easily belifted out and replaced by other tubes and coils.

According to the invention moreover, the means for controlling theoutlet temperature of the fluid from the secondary circuits comprisesvalve means adapted to regulate the rate of flow of fluid to each partof the secondary circuit.

The invention is diagrammatically illustrated by way of example in theaccompanying drawing which is a sectional elevation of a heat exchangeraccording to the invention.

As shown the heat exchanger comprises three vertical concentric tubes 1,2 and 3, the outer tube 3 being lined with a refractory material 4. Acentral circular space 5 and annular spaces 6 and 7 are thus formed. Theannular space 7 is provided with advantageously spiral tubular coils 8and 9. The space 5 is in communication "ice with the coil 8 through aheader 10 and the space 6 is in communication with the coil 9 by meansof a header 11. The coils 8 and 9 are in communication one with anotherby means of the header 11. A further header 12 is provided at the upperend of the coil 9 communicating with an outlet port 13. A port 14communicating with the space 7 is provided at the upper end of theexchanger as inlet for the primary fluid, and a port 15 is provided atthe lower end of the exchanger for outlet of the primary fluid. Thefluid for the secondary circuits enters by a pipe line 16 and passes byway of a valve 17 and pipes 18 and 19 to inlet ports 20 and 2 1communicating with the spaces 5 and 6 respectively.

In operation the fluid passes from line 16 to the valve 17 where it issplit into two streams to pass along pipes 18 and 19. The fluid frompipe 18 passes down the central space 5 to the lower end of theexchanger where it enters the coil 8 by means of the header 10. Fluidfrom pipe 19 passes down the space 6 to the: header 11 where it mixeswith fluid from the coil 8. The mixed fluids pass through the coil 9 tothe header 12 and out of the exchanger at the port 13. During the timethat it is passing through the coils 8 and 9 it is in heat-exchangingrelation through the walls of the coil tubes with the primary fluidwhich is passing over the coils in the space 7. Assuming that theprimary fluid is at a higher temperature than the secondary fluid, thesecondary fluid will be heated as it passes through the exchanger. It isapparent that the fluid from the pipe 18 takes a longer path through theexchanger than the fluid from the pipe 19 and thus will absorb more heatfrom the primary fluid. Thus by regulating the proportion of flowsupplied to the spaces 5 and 6 the outlet from port 13 can be regulatedbetween the limits of very hot, that is to say all the fluid suppliedthrough space 5, and cool, that is to say all the fluid supplied throughspace 6.

The invention further includes the feature that two feeds of secondaryfluid can be applied to the exchanger at diiferent temperatures. Feedpipe 22 communicating with pipe 18 and feed pipe 23 communicating withpipe 19 are provided for this purpose. Thus a cool fluid suppliedthrough pipe 22 passes through space 5 and coil 3 and by the time itreaches header 11 is raised to approximately the same temperature as arelatively hot fluid supplied through pipe 23 and space 6. Flow controlvalves 24, 25 are provided on the pipes 22, 23 respectively.

The ratio of lengths of the coils 8 and 9 may easily be changed bysplitting the joint 26 and removing the tube bundle formed by tubes 1and 2 and coils 8 and 9 from the outer tube 3 and replacing them by afurther tube bundle comprising coils and tubes of the desired lengths.

I claim:

1. A heat exchanger, comprising:

an outer casing having a fluid inlet and a fluid outlet arranged so thata first fluid can flow from said inlet through said casing to saidoutlet,

a first conduit extending into said outer casing, said first conduithaving a closed end portion within said outer casing spaced from theinner surface or" said casing and an open end portion externally of saidouter casing and forming an outlet port for a second fluid,

a second conduit extending into said first conduit and having an openend portion externally of said first conduit and forming an inlet portfor said second fluid, said second conduit having an end portionpositioned within said first conduit,

said second conduit spaced from said first conduit and forming a firstchamber between the outer surface of said second conduit and the innersurface of said first conduit,

means connecting a portion of said second conduit outer surface to saidfirst conduit inner surface and forming a second chamber within saidfirst conduit communicating with said second conduit and providing aflow path for said second fluid between said second conduit and saidsecond chamber within said first conduit, and

a plurality of heat exchange tubes communicating at one end with saidfirst chamber and at the other end with said second chamber and therebyforming a flow path for said second fluid between said second chamberand said first chamber.

2. A heat exchanger as set forth in claim 1 in which said outer casingincludes a cylindrical vertical shell having a closed top portion and abottom portion forming a heat exchange chamber therein,

said top portion having an aperture therethrough, and

said first conduit extending through said aperture and secured to saidtop portion so that said first conduit is suspended in said heatexchange chamber from said top portion with said first conduit closedend portion spaced from the inner surface of said bottom portion.

3. A heat exchanger as set forth in claim 1 in which said second conduitis arranged concentrically within said first conduit and forming anannular first chamber therebetween for receiving said second fluid fromsaid heat exchange tubes.

4. A heat exchanger as set forth in claim 2 in which said second chamberextends to a location adjacent said vertical shell bottom portion andsaid first chamber is positioned adjacent said vertical shell closed topportion and said heat exchange tubes extend substantially throughout thelength of said vertical shell between said second chamber and said firstchamber.

5. A heat exchanger, comprising:

an outer casing having a fluid inlet and a fluid outlet arranged so thata first fluid can flow from said inlet through said casing to saidoutlet, first and second conduit means disposed within said casing inheat exchange relation with the fluid flowing between the inlet and theoutlet of said casing, the first and second conduit means havingcorresponding one ends connected to each other so that a second fluidcan flow in series through both conduit means,

first supply means for supplying the second fluid to the other end ofsaid first conduit means and second supply means for supplying thesecond fluid to a point in circuit between the two conduit means wherebythe second fluid is supplied at two different points to said conduitmeans,

a common outlet for the second fluid connected to the other end of thesecond conduit means, and

means for controlling the rates of flow of the second fluid through thefirst supply means and the second supply means to control thetemperature of the secnd fluid at the common outlet.

6. An exchanger according to claim 5, in which said means forcontrolling the rates of flow in the first and second supply meanscomprises valve means adapted to regulate the rate of flow of fluid toeach of said supply means,

7. A heat exchanger according to claim 5, in which said casing and saidfirst and second supply means are defined by three spaced-apartconcentric tubes, the outermost tube forming said casing and having saidinlet and said outlet for said first fluid connected thereto so that thefirst fluid flows through the space between the outermost tube and theintermediate tube, the innermost tube forming one of said supply meansand the space between the innermost tube and the intermediate tubeforming the other of said supply means.

8. A heat exchanger according to claim '7, in which said conduit meansare each provided by helically coiled piping located in the spacebetween said outermost tube and said intermediate tube; the two conduitmeans being arranged in cnd-to-end relation within said space.

9. An exchanger according to claim 8, in which one end of said firstconduit is in communication with said innermost tube, the other end ofsaid first conduit is in communication with the adjacent end of saidsecond conduit and with said intermediate tube and the other end of saidsecond conduit being in communication with said common outlet.

16. A heat exchanger, comprising:

an elongated outer tube having an inlet port adjacent one end thereofand an outlet port adjacent the other end thereof, an intermediate tubeand an inner tube disposed within and spaced from said intermediatetube, said intermediate tube being disposed concentrically within andspaced from said outer tube, said inner tube defining a central openingand the space between said intermediate and inner tubes defining anannular passageway surrounding and isolating from said central opening,two sets of heat exchange conduits disposed in the space between saidouter tube and said intermediate tube and arranged in end-to-endrelation therewithin,

means connecting said central opening to one end of one of said sets ofconduits so that fluid flowing through said central opening will flowthrough said one set of conduits,

means connecting the other end of said one set to one end of the otherset and means connecting said annular passageway to said one end of saidother set so that fluid flowing through said one set and fluid flowingthrough said annular passageway will both flow through said other set,

means providing a common outlet connected to the other end of said otherset, and

means for supplying fluid to said central opening and said annularpassageway at individually controllable rates of flow in order tocontrol the temperature of the fluid at the common outlet.

No references cited.

ROBERT A. OLEARY, Primary Examiner.

T. W. STREULE, Assistant Examiner.

1. A HEAT EXCHANGER, COMPRISING: AN OUTER CASING HAVING A FLUID INLETAND A FLUID OUTLET ARRANGED SO THAT A FIRST FLUID CAN FLOW FROM SAIDINLET THROUGH SAID CASING TO SAID OUTLET, A FIRST CONDUIT EXTENDING INTOSAID OUTER CASING, SAID FIRST CONDUIT HAVING A CLOSED END PORTION WITHINSAID OUTER CASING SPACED FROM THE INNER SURFACE OF SAID CASING AND ANOPEN END PORTION EXTERNALLY OF SAID OUTER CASING AND FORMING AN OUTLETPORT FOR A SECOND FLUID, A SECOND CONDUIT EXTENDING INTO SAID FIRSTCONDUIT AND HAVING AN OPEN END PORTION EXTERNALLY OF SAID FIRST CONDUITAND FORMING AN INLET PORT FOR SAID SECOND FLUID, SAID SECOND CONDUITHAVING AN END PORTION POSITIONED WITHIN SAID FIRST CONDUIT, SAID SECONDCONDUIT SPACED FROM SAID FIRST CONDUIT AND FORMING A FIRST CHAMBERBETWEEN THE OUTER SURFACE OF SAID SECOND CONDUIT AND THE INNER SURFACEOF SAID FIRST CONDUIT, MEANS CONNECTING A PORTION OF SAID SECOND CONDUITOUTER SURFACE TO SAID FIRST CONDUIT INNER SURFACE AND FORMING A SECONDCHAMBER WITHIN SAID FIRST CONDUIT COMMUNICATING WITH SAID SECOND CONDUITAND PROVIDING A FLOW PATH FOR SAID SECOND FLUID BETWEEN SAID SECONDCONDUIT AND SAID SECOND CHAMBER WITHIN SAID FIRST CONDUIT, AND APLURALITY OF HEAT EXCHANGE TUBES COMMUNICATING AT ONE END WITH SAIDFIRST CHAMBER AND AT THE OTHER END WITH SAID SECOND CHAMBER AND THEREBYFORMING A FLOW PATH FOR SAID SECOND FLUID BETWEEN SAID SECOND CHAMBERAND SAID FIRST CHAMBER.